ref: 8cacd2cc0aa7bc7b51c0017edcd6a49db5b4f95e dir: /sys/src/libc/386/387/tan.s/
TEXT tan(SB), $0 FMOVD a+0(FP), F0 FPTAN FMOVDP F0, F0 /* get rid of extra 1.0 */ RET